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Full text of "The manufacture and properties of iron and steel"

232                          METALLURGY OF IRON'AND STEEL.
Per cent.
Silicon..........................                       1.50
Carbon   ........................                       3.00
Iron in slag.
Combined......................    1.8
Snot  ...........................    0.7               2.50
Total   ......................                       7.00
Calculation of increment in converter:
100 tons pig-Iron          @ $11.00                       $1100.00
93 tons metal cost                                          1100.00
1 ton metal                                                        11.83
Increment                                                           .83
Calculation of increment in open-hearth furnace:
40 tons metal              @ $11.83                      ?473.20
%   ton  ore                @     4.00                            2.00
1/3 ton ferro             @   60.00                          20.00
39.12 tons steel   (3% loss)                               495.20
1 ton steel                                                          12.66
Increment                                                           .83
Synopsis:
Increment in converter......................    0.83
Increment In open-hearth...................    0.83
Total increment.......................    1.66
The term "increment" denotes the item of cost caused by the oxidation of part of the metal, and this increment is the same whether much or little ore is used, as the gain in weight from reduction of iron balances the cost of the ore. Whatever changes are made rnv the figures, the increment in the converter must be nearly the same,, as in the manufacture of steel, with the exception of the recar-.. burizer, and this is found in the cost sheets of the open-hearth fur-.,, nace. With this item omitted, the increment in the duplex process, will be the sum of the increments in the Bessemer and open-hearth, processes.
It is necessary, therefore, that the, duplex process should offer, positive economies to offset the higher increment charge, and this it fails to do. The cost of running a Bessemer plant for this pur-, pose will be almost exactly the same as for making soft steel. There, is scarcely an item save that of molds which will not be the same as if the molten metal from the converter were to go to a rolling mill. But it does not go to a rolling mill; it goes to an open-hearth